The aim of the Neuroprotection Exploratory Trials in Parkinson's Disease (NET-PD) is to evaluate whether selected agents slow the clinical progression of Parkinson's Disease. NET-PD was designed to enroll patients in a series of pilot studies and clinical trials of new agents for the treatment of Parkinson's Disease. The role of the clinical sites is to identify, screen, enroll, treat and follow patients in these trials; to reportthe data in a timely manner to the data coordinating center, and to report adverse effects among enrolled patients. Currently, NET-PD is conducting the LS-1 study, a multi-center, double-blind, phase III clinical trial designed to determine whether or not creatine is more effective than placebo in slowing the clinical decline in Parkinson's Disease patients with early, treated Parkinson's Disease.